Certain forms of surgery require irrigation fluids to clean or distend a body cavity or portion. For example, cystoscopy and endoscopic transurethral prostatectomy require the continuous irrigation of the body cavity through the endoscope. In addition, electro-surgical procedures often require continuous irrigation of the body portion which comprises the operative field.
Arthroscopy is a procedure by which a joint, e.g., elbow, ankle or knee is visually examined with an arthro-endoscope, which may include a lens system to enable direct visual examination of the joint or a fiber-optic probe which may be linked to electronic imaging devices. Such tools have long been used as instruments for the diagnosis of various joint ailments.
Arthroscopic surgery is an extension of diagnostic arthroscopy, and early successes include the biopsy of the synovial membrane and medial menisectomy. More recently, specialized arthroscopic instruments and surgical techniques have been developed. It is now common to use motorized instruments to aid in the trimming of the meniscal rim as well as the articular cartilage. In addition, electro-surgical techniques have been developed which enable the precise cutting, separation or coaptation of various tissues, or the coagulation of coaptation of localized vasculature.
Irrigation fluids have long been employed to distend body portions which are endoscopically examined or treated. For example, distention of the knee joint is required in order to allow the insertion of the endoscopic instrument therein. In addition, arthroscopic surgical procedures require continuous irrigation to remove surgical debris. For example, motorized instruments require large volumes of irrigation fluid, i.e., up to 10-12 liters when synovial resection or meniscal surgery is performed.
Irrigation fluids, whether used for arthroscopy or other endoscopic operations such as urethral recsetomy, are selected according to rigid requirements. The irrigant must be isotonic (i.e. isosmotic: exerting the same osmotic pressure as ambient body fluids), non-viscous, non-antigenic and non-toxic. In addition, it should be easily sterilizable and optically clear. In addition, it would be advantageous for the irrigant to have a long shelf life in a concentrated form and be substantially inexpensive.
Various forms of irrigating fluids have been employed. Sterile water has been used for a number of years by various arthroscopists as distilled water is substantially non-conductive, and thus the high potentials required by electrosurgery may be employed without effecting either the patient or the surgeon. However, water is hemolytic and hypotonic and thus tends to add fluids to the surrounding tissue and extract hemoglobin from blood cells, with concomitant damage thereto. For example, hypotonic water solutions may cause water intoxication which leads to disruption of the central nervous system and can result in nausea, somnolence and even death. Isotonic salt solutions such as normal saline have also been used, as such solutions are readily available and are known to have relatively physiological osmotic properties. However, normal saline has a pH of about 5.0, well below the body pH of about 7.4. When large volumes of irrigant are necessary for extended arthroscopic surgery, the physiology of the surgical area may be significantly altered due to this pH difference. Moreover, ionic salt solutions are obviously unsatisfactory for electro-surgery because of their conductivity.
Various non-ionic solutions have been enployed, but have presented additional problems. For example, while isotonic, sugar solutions have been found to be viscous and sticky and are thus unpleasant for the surgical staff. Sugar solutions also cause visual disturbances when in motion, and when concentrated sugar solutions are sterilized by heat they develop an objectional color which affects the endoscopic viewing field. The sugar solutions generally available include sorbitol, manitol and combinations thereof. The use of urea or other non-ionic salt solutions has also been attempted and such solutions present certain advantages with regard to optical clarity. However, urea hemolyzes red blood cells and is therefore as dangerous, if not more so, than water. Protein based mixtures such as albumin solutions produce undesired antigenic responses which may disrupt the entire immunologic system and, as they are derived from blood sources, are unreasonably expensive.
A currently accepted irrigating solution is an isotonic solution of glycine (aminoaecetic acid, NH.sub.2 CH.sub.2 COOH). While glycine solutions offer some advantages, it has some conductivity and has a solubility that is below that necessary to allow the preparation of an aqueous concentrate. In addition, glycine solutions have a pH below that of normal body fluids, tend to cause protein coagulation and tend to precipitate when exposed to the high temperatures at the tip of the electro-surgical probe. Moreover, glycine solutions are absorbed by the body and may be toxic, and glycine is substantially more expensive than many of the alternatives heretofore described.
Accordingly, it has been a desideratum to provide an irrigating solution for endoscopic diagnosis and surgery which is isotonic, non-viscous, non-precipitating at the temperatures occasioned by such surgery, non-antigenic, and non-toxic; which is optically clear at high magnification, is inexpensive and doesn't alter the body chemistry of the treated portion; and which is easily sterilizable and capable of being distributed as a concentrated solution precursor having a long shelf life.
We have discovered a surgical irrigation solution which overcomes the foregoing problems, and provides additional advantages over solutions presently known. The irrigation solution of the present invention is optically clear at extreme magnification and is non-electrolytic so as to allow its use in any form of endoscopic examination or surgery. It is non-antigenic, non-toxic and is isotonic such that it does not alter body chemistry or affect the viability of body cells in the operative area. The solution of the present invention is inexpensive and is not viscous or sticky, so that it may be used in substantial amounts and without the discomfort heretofore present in the use of non-electrolytic sugar-based irrigating solutions. The solution is also easily sterilizable and may be stored in concentrated form for extended periods.
According to the present invention, a surgical irrigation solution is provided which comprises a 2% to 3.5% glycerine-water solution which is substantially isotonic, having an osmolality of from about 200 to about 350 milliosmoles. Preferably, the solution contains glycerine in an amount of from 2.8 to 3.0% and thus having an osmolality of from 280 to 300 milliosmoles.